This invention relates to the stacking of fan-folded webs of paper from a line printer or similar device.
A web of paper is usually fed from a printing mechanism for stacking in folded form. Various paper stacking devices have been devised to insure orderly folding and stacking of the paper after it is ejected from the printer. However, prior paper stacking apparatus of the foregoing type have not been satisfactorily reliable in regard to continuous synchronization of web feed and folding motions. It is, therefore, an important object of the present invention to provide a relatively simple, yet effectively reliable, synchronizing system for a fan-folded web stacker capable of handling all types of paper format with a minimum of operator intervention.
In accordance with the present invention, a fan-foled web from a high speed printer or the like is fed into a buffer zone or bin and when the paper reaches the bottom of the bin, a sensor detects the web to start a paper stacking cycle. During the paper stacking cycle, the paper web is withdrawn from the buffer zone by tractor feed devices, the paper being fed through an oscillating folder chute device by means of which the paper is folded as it is deposited onto a stack within a receiving bin. Since the paper web is folded at spaced positions within the receiving bin, the folding chute is oscillated through a fixed arc of 45.degree. , for example, at a rate synchronized with the feeding motion of the web. The feeding and folding motions are controlled by two separate stepper motors utilizing a common source of pulses that are digitally divided by different factors in order to produce driving pulses at different pulse rates. The number of common pulses and the division factors are selected in accordance with the feeding velocity and paper dimensions in order to produce the correct motion relationships. This pulse dividing drive arrangement is such that any errors introduced are non-accumulative. Monitor circuits are utilized to provide error detection in the event of any malfunction or deviation from the synchronized relationships normally maintained.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof, wherein like numerals refer to like parts throughout.